Inductor embedded in substrate, manufacturing method thereof, micro device package, and manufacturing method of cap for micro device package

ABSTRACT

An inductor embedded in a substrate, including a substrate, a coil electrode formed by filling a metal in a spiral hole formed on the substrate, an insulation layer formed on the substrate, and an external connection pad formed on the insulation layer to be connected to the coil electrode. The inductor-embedded substrate can be used as a cap for a micro device package by forming a cavity on its bottom surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Korean Patent Application No.2005-55796, filed on Jun. 27, 2005 in the Korean Intellectual PropertyOffice, the entire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Apparatuses and methods consistent with the present invention relate toan inductor, and more particularly, to an inductor embedded in asubstrate, a manufacturing method thereof, a micro device package usingthe same, and a manufacturing method of a cap for the micro devicepackage.

2. Description of the Related Art

Recently, portable electronic apparatuses such as video apparatuses,personal computers, cellular phones and flat type displays have beenrapidly reduced in thickness and size. Electronic circuits includingmagnetic devices such as inductors and transformers that are built inthe above apparatuses are strongly required to cope with the small-size,high integration, and radio-frequency (RF) tendencies of the devices.

A high-Q inductor is a common characteristic of most of thecommunication semiconductor devices. A related art method for formingthe inductors in the semiconductor device includes depositing a metalhaving a thickness of at least 3 μm on the top layer of the circuit.However, this method requires an area over 300 μm×300 μm to form teninductors. The area is not used for the other circuits due toelectromagnetic interferences. That is, the general inductor has a lowinductance as compared with design space utilization. It is thereforedifficult to manufacture an inductor having a high Q factor and a lowinsertion loss in the restricted space.

In addition, a current process technique for forming a high-Q inductorusing photoresist and copper requires a two or higher mask level and atwo or higher exposure step. However, an inductor having an air gap isnot compatible with the current process technology. That is, theinductor having the air gap needs a high difficulty process. Especially,in wet etching for floating the structure, the structure is adhered tothe substrate. Moreover, the inductor having the air gap does not showsufficient solidity as a device.

On the other hand, a packaging technology for making a few devices witha single chip is required with the small size and high integrationtendency of the electronic circuits. The general inductor and themanufacturing method thereof cannot embody the single chip package.

SUMMARY OF THE INVENTION

The present invention provides an inductor embedded in a substrate whichhas a high inductance as compared with design space utilization.

Further, the present invention provides an inductor embedded in asubstrate which simplifies the whole manufacturing process, improvessolidity and has a high Q factor and a low insertion loss.

Additionally, the present invention provides an inductor embedded in asubstrate which can easily compose a single chip package with otherdevices.

Further, the present invention provides a manufacturing method of theinductor embedded in the substrate which has the above characteristics.

The present invention also provides a micro device package using theinductor embedded in the substrate which has the above characteristics,and a manufacturing method of a cap for the micro device package.

According to an aspect of the invention, there is provided an inductorembedded in a substrate, including a substrate and a coil electrode. Thecoil electrode comprises metal, and fills a hole formed on thesubstrate.

In an exemplary embodiment, the coil electrode is disposed in a linearspiral shape or curved spiral shape. One of ordinary skill in the artwill recognize that the shapes of the exemplary embodiments are notintended to be limit other shapes from being used.

Also, the substrate may be a Si substrate, and the coil electrode may bemade of gold, silver or copper.

According to another aspect of the invention, there is provided aninductor embedded in a substrate, including: a substrate; a coilelectrode formed by filling a metal in a hole formed on the substrate;an insulation layer formed on the substrate; and an external connectionpad formed on the insulation layer to be connected to the coilelectrode.

The external connection pad may be made of the same metal as the coilelectrode, and the insulation layer may be made of a low dielectricmaterial.

According to yet another aspect of the invention, there is provided amanufacturing method of an inductor embedded in a substrate, including:forming a seed layer for plating on a bottom surface of a substrate;forming an etch mask pattern on the top surface of the substrate;forming a hole on the substrate according to the etch mask pattern;forming a coil electrode by filling a metal in the hole by a platingprocess using the seed layer; forming an insulation layer pattern on thetop surface of the substrate; and forming an external connection pad onthe insulation layer.

According to yet another aspect of the invention, there is provided amicro device package, including: a package body on which a micro deviceand an electrode pad are formed; and a cap coupled to the package body,for sealing up the micro device. The cap includes: a substrate having acavity on its bottom surface; an inverter having a coil electrode formedby filling a metal in a hole formed on the substrate; a deviceconnection pad formed on the bottom surface of the substrate to contactthe electrode pad of the package body; and a second external connectionpad connected to the device connection pad and exposed through the topsurface of the substrate.

In an exemplary embodiment, the coil electrode is disposed in a linearspiral shape or curved spiral shape.

The substrate may be a Si substrate, the coil electrode may be made ofgold, silver or copper, and the second external connection pad may bemade of the same metal as the coil electrode.

In another exemplary embodiment, the micro device is amicroelectromechanical system (MEMS) device such as an RF duplexer and amicro switch.

According to yet another aspect of the invention, there is provided amanufacturing method of a cap for a micro device package, including thesteps of: forming a cavity on a bottom surface of a substrate; forming aseed layer for plating on the bottom surface of the substrate includingthe cavity; forming an etch mask pattern on the top surface of thesubstrate; forming a hole on the substrate according to the etch maskpattern; forming a coil electrode by filling a metal in the hole by aplating process using the seed layer; forming an insulation layerpattern on the top surface of the substrate; forming an externalconnection pad on the insulation layer; and forming an electrode pad anda sealing pad by patterning the seed layer on the bottom surface of thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above aspects of the present invention will be more apparent bydescribing certain exemplary embodiments of the present invention withreference to the accompanying drawings, in which:

FIGS. 1A and 1B are a perspective view and a cross-sectional viewillustrating an inductor embedded in a substrate in accordance with anexemplary embodiment of the present invention.

FIGS. 2A and 2B are a perspective view and a cross-sectional viewillustrating a cap for a micro device package having the inductor ofFIG. 1.

FIG. 3 is a cross-sectional view illustrating one example of the microdevice package using the cap of FIG. 2 according to an exemplaryembodiment of the present invention.

FIGS. 4A to 4G are process views illustrating a manufacturing method ofa cap for a micro device package having an inductor embedded in asubstrate in accordance with an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

An inductor embedded in a substrate, a manufacturing method thereof, amicro device package using the same, and a manufacturing method of a capfor the micro device package in accordance with the present inventionwill now be described in detail with reference to the accompanyingdrawings. Well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

Referring to FIGS. 1A and 1B, an inductor includes a substrate 10 and acoil electrode 20.

A spiral hole 11 is formed on the substrate 10 to pass through thesubstrate 10 in the up/down (substantially vertically) direction. Thecoil electrode 20 is embedded in the substrate 10 by filling a metal inthe hole 11. An insulation layer 30 is formed on the top surface of thesubstrate 10. A bridge structure external connection pad 40 is formed onthe insulation layer 30 to be connected to the coil electrode 20.

The substrate 10 is a silicon (Si) or glass substrate. Especially, ahigh resistivity Si substrate is advantageous. In exemplary embodiments,the coil electrode 20 is made of a metal having high electricconductivity, such as gold, silver and copper, and the externalconnection pad 40 is made of the same metal as the coil electrode 20. Onthe other hand, the insulation layer 30 is made of a low dielectricmaterial. In addition, the hole 11 can be formed in other shapes, suchas a linear spiral shape or curved spiral shape, for example.

In accordance with the present invention, an inductor embedded in thesubstrate provides the coil electrode 20 having a high aspect ratiosection, thereby improving a Q factor and reducing an insertion loss.

FIGS. 2A and 2B are a perspective view and a cross-sectional viewillustrating the cap for the micro device package having the inductorembedded in the substrate as explained above. As illustrated in FIGS. 2Aand 2B, the structure of the cap for the micro device package issubstantially similar to the structure of FIG. 1, except that a cavity150 is formed on a bottom surface of a substrate 110, a deviceconnection pad 160 and a sealing pad 170 are formed at both sides of thecavity 150, and a second external connection pad 145 is formed on thetop surface of the substrate 110. Accordingly, related referencenumerals are used and detailed explanations are omitted. Referencenumeral 180 denotes a member for electrically connecting the deviceconnection pad 160 to the second external connection pad 145 on thesubstrate 110.

FIG. 3 is a cross-sectional view illustrating the micro device packagehaving the cap 100 of FIG. 2. As shown in FIG. 3, in the micro devicepackage, a micro device 210, an electrode pad 220 and a sealing pad 230are formed in proper positions of a package body 200. The cap 100 iscoupled to the package body 200, so that the micro device 210 can bepositioned in the cavity 150 of the cap 100. The coupling process iscarried out by using an adhesive or solder 300.

In the micro device package structure, the micro device can be a MEMSdevice requiring an operation space. In more detail, the MEMS device canbe an RF duplexer or a micro switch.

The manufacturing method of the cap for the micro device package havingthe inductor embedded in the substrate in accordance with the presentinvention will now be described with reference to FIG. 4.

As illustrated in FIG. 4A, a cavity 150 is formed by etching apredetermined area of a lower portion of a substrate 110. In the casethat the inductor embedded in the substrate is used as a simple inductoras shown in FIG. 1, it is not necessary to form the cavity 150. Theposition of the cavity 150 corresponds to a device area of a packagebody 200. The cavity 150 may be formed according to a wet etching methodusing chemical solution, such as acetic acid, hydrofluoric acid, andphosphoric acid, or a dry etching method using gas, plasma and ion beam.

As shown in FIG. 4B, a seed layer 310 for plating is formed bydepositing a metal on the bottom surface of the substrate 110 includingthe surface of the cavity 150.

As depicted in FIG. 4C, an etch mask pattern 320 is formed on the topsurface of the substrate 110, and a hole 111 having a high aspect ratiois processed by dry etching that is one of the bulk micromachiningmethods. The hole 111 is formed in a square spiral shape. In exemplaryembodiments, the mask pattern 320 is made of photoresist having athickness of 10 μm, and the dry etching is the ICP RIE (induced coupledplasma ion etching). After the dry etching, the mask pattern 320 isremoved.

Referring to FIG. 4D, a coil electrode 120 is formed by filling a metalin the hole 111 by the plating process using the seed layer 310.Preferably, the plating process is an electroplating process, and theplating material is a metal having high electric conductivity, such asgold, copper and silver.

As illustrated in FIG. 4E, an insulation layer 130 pattern is formed onthe top surface of the substrate 110. Preferably, the insulation layer130 is made of a low dielectric material, for example, benzocyclobuteneand polyimide. Here, the insulation layer 130 serves to electricallyinsulate an external connection pad 140 connected to the coil electrode120 and the middle portion of the coil electrode 120. In order tominimize an unnecessary capacitance of the inductor, the insulationlayer 130 is made of a low dielectric material such as benzocyclobuteneand polyimide.

As a frequency rises, self energy of the inductor gradually decreasesand energy by a capacitance gradually increases. Therefore, the inductoris not normally operated, and a self resonance frequency operated as acapacitor is generated. In order to solve the above problems, theinsulation layer 130 may be made of a low dielectric material andthickened to minimize a parasitic capacitance between the coil electrode120 and the external connection pad 140.

Referring to FIG. 4F, the external connection pad 140 is formed on theinsulation layer 130. The external connection pad 140 is made of thesame material as the coil electrode 120.

As shown in FIG. 4G, an electrode pad 160 and a sealing pad 170 areformed by patterning the seed layer on the bottom surface of thesubstrate 110. As a result, the micro device package having the inductorof FIG. 3 can be manufactured by coupling the cap 100 for the microdevice package manufactured by the above process to the package body200.

As discussed earlier, in accordance with the present invention, sincethe inductor is formed by embedding the coil electrode in the substrate,the inductor has the high inductance as compared with design spaceutilization. In addition, the size of the product using the inductor canbe reduced.

Furthermore, because the inductor-embedded substrate is used as the capfor the micro device package, the inductor and other devices can bepackaged as a single chip, to simplify the electronic circuit andimprove the freedom degree of circuit design.

The foregoing exemplary embodiments are not to be construed as limitingthe present invention. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments of the present invention is intended to be illustrative, andnot to limit the scope of the claims, and many alternatives,modifications, and variations will be apparent to those skilled in theart.

1. An inductor, comprising: a substrate; and a coil electrode embeddedin the substrate, the coil electrode comprising a metal.
 2. The inductoras claimed in claim 1, wherein the coil electrode is formed in a linearspiral shape.
 3. The inductor as claimed in claim 1, wherein the coilelectrode is formed in a curved spiral shape.
 4. The inductor as claimedin claim 1, wherein the substrate is an Si substrate.
 5. The inductor asclaimed in claim 1, wherein the coil electrode comprises gold, silver,copper, or a combination thereof.
 6. An inductor, comprising: asubstrate; a coil electrode embedded in the substrate, the coilelectrode comprising a metal; an insulation layer formed on thesubstrate; and an external connection pad formed on the insulation layerto be connected to the coil electrode.
 7. The inductor as claimed inclaim 6, wherein the coil electrode is formed in a linear spiral shape.8. The inductor as claimed in claim 6, wherein the coil electrode isformed in a curved spiral shape.
 9. The inductor as claimed in claim 6,wherein the substrate is an Si substrate.
 10. The inductor as claimed inclaim 6, wherein the coil electrode comprises gold, silver, copper, or acombination thereof.
 11. The inductor as claimed in claim 10, whereinthe external connection pad is made of the same metal as the coilelectrode.
 12. The inductor as claimed in claim 8, wherein theinsulation layer is made of a low dielectric material.
 13. Amanufacturing method of an inductor, comprising: forming a seed layerfor plating on a bottom surface of a substrate; forming an etch maskpattern on a top surface of the substrate; forming a hole on thesubstrate according to the etch mask pattern; forming a coil electrodeby filling a metal in the hole by a plating process using the seedlayer; forming an insulation layer pattern on the top surface of thesubstrate; and forming an external connection pad on the insulationlayer.
 14. A micro device package, comprising: a package body on which amicro device and an electrode pad are formed; and a cap coupled to thepackage body, for sealing up the micro device, wherein the capcomprises: a substrate having a cavity on its bottom surface; aninverter having a coil electrode formed by filling a metal in a holeformed on the substrate; a device connection pad formed on the bottomsurface of the substrate to contact the electrode pad of the packagebody; and a second external connection pad connected to the deviceconnection pad and exposed through a top surface of the substrate. 15.The micro device package as claimed in claim 14, wherein the coilelectrode is formed in a linear spiral shape.
 16. The micro devicepackage as claimed in claim 14, wherein the coil electrode is formed ina curved spiral shape.
 17. The micro device package as claimed in claim14, wherein the substrate is a Si substrate.
 18. The micro devicepackage as claimed in claim 14, wherein the coil electrode comprisesgold, silver, copper, or a combination thereof.
 19. The micro devicepackage as claimed in claim 18, wherein the second external connectionpad is made of the same metal as the coil electrode.
 20. The microdevice package as claimed in claim 14, wherein the micro device is aMEMS device.
 21. The micro device package as claimed in claim 20,wherein the MEMS device is an RF duplexer or a micro switch.
 22. Amanufacturing method of a cap for a micro device package, comprising:forming a cavity on a bottom surface of a substrate; forming a seedlayer for plating on the bottom surface of the substrate including thecavity; forming an etch mask pattern on a top surface of the substrate;forming a hole on the substrate according to the etch mask pattern;forming a coil electrode by filling a metal in the hole by a platingprocess using the seed layer; forming an insulation layer pattern on thetop surface of the substrate; forming an external connection pad on theinsulation layer; and forming an electrode pad and a sealing pad bypatterning the seed layer on the bottom surface of the substrate.